Replace prevention theory posits that coping behaviors are instrumental in avoiding relapse and coping behaviors have been demonstrated to be powerful determinants of smoking cessation success. Efficacy and outcome expectations are hypothesized to be casual determinants of coping behaviors and these variables are among the better predictors of smoking abstinence. Moreover, behavioral interventions based on relapse prevention theory are effective. They instill coping skills and these skills mediate intervention effects on smoking abstinence. However, a major barrier to the use of behavioral treatments for smoking cessation is that most smokers appear to prefer to quit with minimal or no help from clinicians or formal programs. Moreover, while the advent of over-the-counter nicotine replacement products (i.e., patch, gum) increases the availability of proven pharmacologic treatments for smoking cessation, smokers no longer need to see a physician to obtain these products. Thus, smokers may be even less likely to seek out or receive smoking cessation advice or counseling than previously, despite the demonstrated efficacy of behavioral treatments. This proposal attempts to increase the accessibility and acceptability of a relapse prevention based behavioral treatment for smoking cessation by using a small hand-held computer to deliver the intervention. The intervention will be used as an adjuvant to an over-the-counter nicotine patch therapy program. Each participant's computer-delivered intervention will be individualized prior to quitting based on relapse prevention theory and state-of-the-art "ecological momentary assessment" techniques. Using the computer, efficacy and outcome expectations for various coping behaviors will be measured in real- time during naturally occurring temptation episodes. These expectation ratings will then be used to personalize each participant's intervention. The specific aims of this proposal are to: 1) Develop and evaluate the efficacy of an individualized, computer-delivered smoking cessation intervention, and 2) Examine how hypothesized treatment mechanisms (coping behaviors, self-efficacy, processes of change, negative affect, perceived stress) mediate the effects of computer-delivered treatment on abstinence. Unlike conventional treatments, the computer-delivered intervention addresses the episodic nature of temptations and relapse by providing smokers with treatment precisely when it is most needed, and allows participants to tailor the intensity of the intervention to their individua needs. Treatment intensity is strongly related to efficacy. Computer- delivered interventions have the potential to produce significant advances in the individualization, accessibility, and acceptability of behavioral treatments for nicotine addiction, and if shown to be effective, would have broad clinical and public health applications.